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Hibernate 一对多外键单向关联
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这种情况很少见，但Hibernate同样允许采用连接表关联1-1.有连接表的1-1同样只需要将N-1的many-to-one元素增加unique="true"属性即可。
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一、模型介绍
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一个人（Person）对应多个地址（Address），比如家庭地址、公司地址。
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二、实体（省略getter、setter方法）
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public class Person1nfk implements Serializable {
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private int personid;
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private String name;
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private int age;
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private Set addresses=new HashSet();
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public class Address1nfk implements Serializable {
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private int addressid;
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private String addressdetail;
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三、表模型
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mysql> desc address_1nfk;
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+---------------+--------------+------+-----+---------+----------------+
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| Field | Type | Null | Key | Default | Extra |
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+---------------+--------------+------+-----+---------+----------------+
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| addressid | int(11) | NO | PRI | NULL | auto_increment |
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| addressdetail | varchar(255) | YES | | NULL | |
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| personid | int(11) | YES | MUL | NULL | |
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+---------------+--------------+------+-----+---------+----------------+
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mysql> desc person_1nfk;
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+----------+--------------+------+-----+---------+----------------+
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| Field | Type | Null | Key | Default | Extra |
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+----------+--------------+------+-----+---------+----------------+
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| personid | int(11) | NO | PRI | NULL | auto_increment |
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| name | varchar(255) | YES | | NULL | |
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| age | int(11) | YES | | NULL | |
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+----------+--------------+------+-----+---------+----------------+
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四、生成的SQL脚本
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/* Formatted on 2007/08/21 10:06 (QP5 v5.50) */
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CREATE TABLE `address_1nfk` (
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`addressid` int(11) NOT NULL auto_increment,
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`addressdetail` varchar(255) default NULL,
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`addresses` int(11) default NULL,
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PRIMARY KEY (`addressid`),
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KEY `FK9B93456DC08D1667` (`addresses`),
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CONSTRAINT `FK9B93456DC08D1667` FOREIGN KEY (`addresses`) REFERENCES `person_1nfk` (`personid`)
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) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=gbk;
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/* Formatted on 2007/08/21 10:07 (QP5 v5.50) */
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CREATE TABLE `person_1nfk` (
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`personid` int(11) NOT NULL auto_increment,
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`name` varchar(255) default NULL,
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`age` int(11) default NULL,
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PRIMARY KEY (`personid`)
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) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=gbk;
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五、映射方法：在实体类Person里面添加Address的集合，即可形成一对多关系。
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<!--映射集合属性，关联到持久化类,inverse="false"表示主控端在Person1nfk端，lazy="false"表示不采用延迟加载-->
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<set name="addresses"
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table="ADDRESS_1nfk"
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cascade="all"
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>
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<!--确定关联的外键列-->
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<key column="personid"/>
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<!--用以映射到关联类属性-->
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<one-to-many class="com.lavasoft.dx._1_n_fk.Address1nfk"/>
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</set>
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<hibernate-mapping>
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<class name="com.lavasoft.dx._1_n_fk.Person1nfk" table="PERSON_1nfk">
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<id name="personid">
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<generator class="identity"/>
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</id>
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<property name="name"/>
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<property name="age"/>
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<!--映射集合属性，关联到持久化类,inverse="false"表示主控端在Person1nfk端，lazy="false"表示不采用延迟加载-->
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<set name="addresses"
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table="ADDRESS_1nfk"
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cascade="all"
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>
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<!--确定关联的外键列-->
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<key column="personid"/>
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<!--用以映射到关联类属性-->
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<one-to-many class="com.lavasoft.dx._1_n_fk.Address1nfk"/>
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</set>
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</class>
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</hibernate-mapping>
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<hibernate-mapping>
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<class name="com.lavasoft.dx._1_n_fk.Address1nfk" table="ADDRESS_1nfk">
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<id name="addressid">
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<generator class="identity"/>
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</id>
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<property name="addressdetail"/>
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</class>
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</hibernate-mapping>
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六、测试方法
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public class Test_1nfk {
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public static void main(String[] args){
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Address1nfk add1=new Address1nfk();
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Address1nfk add2=new Address1nfk();
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Person1nfk p=new Person1nfk();
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add1.setAddressdetail("郑州市经三路");
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add2.setAddressdetail("合肥市宿州路");
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p.setName("wang");
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p.setAge(30);
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p.getAddresses().add(add1);
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p.getAddresses().add(add2);
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Session session= HibernateUtil.getCurrentSession();
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Transaction tx=session.beginTransaction();
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session.save(add1);
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session.save(add2);
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session.save(p);
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tx.commit();
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HibernateUtil.closeSession();
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}
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}
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七、测试结果
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1) :正常保存.
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// session.save(add1);
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// session.save(add2);
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session.save(p);
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Hibernate: insert into PERSON_1nfk (name, age) values (?, ?)
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Hibernate: insert into ADDRESS_1nfk (addressdetail) values (?)
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Hibernate: insert into ADDRESS_1nfk (addressdetail) values (?)
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Hibernate: update ADDRESS_1nfk set personid=? where addressid=?
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Hibernate: update ADDRESS_1nfk set personid=? where addressid=?
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2) :正常保存.
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session.save(add1);
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session.save(add2);
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session.save(p);
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Hibernate: insert into ADDRESS_1nfk (addressdetail) values (?)
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Hibernate: insert into ADDRESS_1nfk (addressdetail) values (?)
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Hibernate: insert into PERSON_1nfk (name, age) values (?, ?)
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Hibernate: update ADDRESS_1nfk set personid=? where addressid=?
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Hibernate: update ADDRESS_1nfk set personid=? where addressid=?
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3) :正常保存.
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session.save(add1);
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session.save(add2);
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// session.save(p);
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Hibernate: insert into ADDRESS_1nfk (addressdetail) values (?)
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Hibernate: insert into ADDRESS_1nfk (addressdetail) values (?)
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本文转自 leizhimin 51CTO博客，原文链接：http://blog.51cto.com/lavasoft/39317，如需转载请自行联系原作者